Electric and gas water heaters are commonly used to provide a reserve of heated water for residential or commercial use. A typical water heater includes inlet piping for supplying cold water to a water tank and outlet piping for supplying heated water to one or more dispensing locations. Water heaters of both the fuel-fired and electrically heated types typically have a tank portion in which pressurized, heated water is stored for on-demand delivery to various types of hot water-utilizing plumbing fixtures such as, for example, sinks, bath tubs and dishwashers.
Heat loss and the associated reduction in energy efficiency is known to occur in water heater systems. During standby periods in which discharge of stored hot water from the tank is not required, it is desirable to substantially reduce heat loss from the stored hot water to cooler areas outside the tank. A significant portion of this heat loss occurs at the water heater inlet and outlet ports through which water is introduced into, and removed from, the water storage tank. Specifically, when water is neither being added to the water storage tank by means of the cold water inlet port nor removed from the water storage tank by means of the hot water outlet port, heat from the hot water from within the water storage tank tends to flow in the form of convection currents upward through the cold water inlet port and the hot water outlet port. Accordingly, these convection currents result in significant heat loss and reductions in water heater system energy efficiency.